Development of small diameter vascular prostheses for long-term implantation would provide an alternative to the use of autologous venous and arterial grafts. The ideal biomaterial for such a device would eliminate thrombosis and minimize smooth muscle cell in growth while maintaining the compliance of natural vasculature. Coverage of the luminal surface of a graft with autologous endothelial cells could, in principle, provide a thromboresistant surface and is a promising approach towards the development of an artificial vascular grafts. Development of artificial grafts requires a fundamental understanding of interactions between biomaterials, endothelial cells, and platelets. The proposed research is based upon the hypothesis that endothelial cell adhesion to biomaterials is dependent upon the extent to which focal adhesions are formed at the cell- substrate interface. Focal adhesion formation appears to be a function of biomaterial surface properties and the conformation and composition of the protein layer which coats all surfaces in contact with flowing blood. Total internal reflection fluorescence (TIRF) will be used to identify and quantitate the formation of focal contacts which are believed to be the physical regions in which focal adhesions form. The adhesive strength of the cells will be determined by brief exposure of the cells to flow and measurement of cell detachment. Surfaces to be examined include bare glass, silanized glass, and polymer coated glass pretreated with different concentrations adhesive protein (e.g. fibronectin). The gross differences in surface hydrophobicity presented by these surfaces should perturb the intermediate protein layer in a manner that results in differences in cell adhesion. The adhesive strength will be correlated to the area of focal contact and the biomaterial properties. This study is novel in that it represents a real time observation of cell attachment site morphology under conditions of variable substrate surface chemistry. In addition, we shall investigate the commonality of endothelial cell and platelet adhesion by observing the latter phenomenon under nearly identical conditions of flow, surface chemistry, and protein intermediate composition.